tjh.dev / kernel
Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel os linux
fork atom

s390: fold kernel_thread_helper() into ret_from_fork()

... and don't bother with syscall return path in case of kernel
threads.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

Al Viro 37fe5d41 65f22a90

+28 -16
+15 -3
arch/s390/kernel/entry.S
··· 331 331 l %r12,__LC_THREAD_INFO 332 332 l %r13,__LC_SVC_NEW_PSW+4 333 333 tm __PT_PSW+1(%r11),0x01 # forking a kernel thread ? 334 - jo 0f 335 - st %r15,__PT_R15(%r11) # store stack pointer for new kthread 336 - 0: l %r1,BASED(.Lschedule_tail) 334 + je 1f 335 + l %r1,BASED(.Lschedule_tail) 337 336 basr %r14,%r1 # call schedule_tail 338 337 TRACE_IRQS_ON 339 338 ssm __LC_SVC_NEW_PSW # reenable interrupts 340 339 j sysc_tracenogo 340 + 341 + 1: # it's a kernel thread 342 + st %r15,__PT_R15(%r11) # store stack pointer for new kthread 343 + l %r1,BASED(.Lschedule_tail) 344 + basr %r14,%r1 # call schedule_tail 345 + TRACE_IRQS_ON 346 + ssm __LC_SVC_NEW_PSW # reenable interrupts 347 + lm %r9,%r11,__PT_R9(%r11) # load gprs 348 + ENTRY(kernel_thread_starter) 349 + la %r2,0(%r10) 350 + basr %r14,%r9 351 + la %r2,0 352 + br %r11 # do_exit 341 353 342 354 # 343 355 # kernel_execve function needs to deal with pt_regs that is not
+13 -3
arch/s390/kernel/entry64.S
··· 352 352 la %r11,STACK_FRAME_OVERHEAD(%r15) 353 353 lg %r12,__LC_THREAD_INFO 354 354 tm __PT_PSW+1(%r11),0x01 # forking a kernel thread ? 355 - jo 0f 356 - stg %r15,__PT_R15(%r11) # store stack pointer for new kthread 357 - 0: brasl %r14,schedule_tail 355 + je 1f 356 + brasl %r14,schedule_tail 358 357 TRACE_IRQS_ON 359 358 ssm __LC_SVC_NEW_PSW # reenable interrupts 360 359 j sysc_tracenogo 360 + 1: # it's a kernel thread 361 + stg %r15,__PT_R15(%r11) # store stack pointer for new kthread 362 + brasl %r14,schedule_tail 363 + TRACE_IRQS_ON 364 + ssm __LC_SVC_NEW_PSW # reenable interrupts 365 + lmg %r9,%r11,__PT_R9(%r11) # load gprs 366 + ENTRY(kernel_thread_starter) 367 + la %r2,0(%r10) 368 + basr %r14,%r9 369 + la %r2,0 370 + br %r11 # do_exit 361 371 362 372 # 363 373 # kernel_execve function needs to deal with pt_regs that is not
-10
arch/s390/kernel/process.c
··· 98 98 99 99 extern void __kprobes kernel_thread_starter(void); 100 100 101 - asm( 102 - ".section .kprobes.text, \"ax\"\n" 103 - ".global kernel_thread_starter\n" 104 - "kernel_thread_starter:\n" 105 - " la 2,0(10)\n" 106 - " basr 14,9\n" 107 - " la 2,0\n" 108 - " br 11\n" 109 - ".previous\n"); 110 - 111 101 int kernel_thread(int (*fn)(void *), void * arg, unsigned long flags) 112 102 { 113 103 struct pt_regs regs;